This invention relates to a method and apparatus for treating flaws existing on the surface of wire-shaped metals such as bearing steel and stainless or the like.
Up to the present, the following methods for treating flaws existing on the surface of wire-shaped wires such as bearing steel and stainless steel have been used:
(a) Peeling all surfaces of wire-shaped metals by applying chipping dyes;
(b) Peeling all surfaces of wire-shaped metals by using a centerless peeling machine;
(c) Grinding the flawed portions by using a hand grinder after visually detecting the flaws;
(d) Grinding marked portions after detection of the flawed portions along the entire length of a wire-shaped metal by an automatic flaw-detecting device and marking of the flawed portions with paint.
However, there are costly drawbacks in methods like (a) and (b) above, such as yield rate dropping and early wearing of the peeling tool. Although methods (c) or (d) remarkably improve the yield rate of the product by peeling only the portions to be removed, they require unbinding of the wire-shaped metal, and visual detection of the flaws along the entire length and all peripheries, or visual detection of the paint-marked portion around the periphery.
Consequently, these methods are difficult to work, inadequate and incur remarkably high labor costs.
It is also known that flaws on the surface of spiral wires, straight wires and steel rods can be automatically removed by cutting, shaving or grinding off by an automatic flaw-removal method comprising the detection of the existence and location of the circumferential and longitudinal flaws on the surface of wires or steel rods by applying a flaw-detecting device; transmission of flaw information detected by a flaw-detecting device to a distance-computing device and to a flaw-cutting device; detection of the running speed of said wires or rods by applying a running speed detecting device; computation of the distance between said detected flaw position and said flaw-cutting device by applying running speed information received from said running speed detecting device or the distance-computing device; activation of the flaw-cutting device by applying distance information of the wires or rods obtained from the distance-computing device; and cutting said detected flaw by applying the flaw-cutting device. Japanese Patent Publication No. 50453/1984.
When the known method is used for removing flaws on the surface of spiral wires, however, it has another disadvantage to be overcome.
The present invention was developed in consideration of the above-mentioned drawbacks, and its first object is to reduce labor costs, to increase product yield rate, to shorten processing time, and to reduce production costs by automatically cutting only the flawed portions of a wire-shaped metal.
However, in order to remove harmful flaws entirely, the following problems must be resolved.
This process contains both a detecting step which locates flaws along circumferential and longitudinal directions of the wire-shaped metal by application of a flaw-detecting device, and a cutting step which automatically cuts and removes any detected flaws by applying a cutting bite, requiring restoration from the irregularity of the diametric shape of the cut portions. If this restoration step was performed on another work line, productivity dropped and production costs rose.
Also, to increase the working efficiency of wire-shaped metal, it is preferable to perform both flaw-detection and automatic flaw-cutting on the same work line. But if dust attaches to the wire-shaped metal, it is apt to transmit a false flaw-detection signal, increasing the number of cuts and increasing the wear on the cutting bites. Further, the more the surface of the metal is cut, the more unnecessary die markings appear, and the die markings deteriorate the metal quality.
Furthermore, even if flaw-detection and automatic flaw-cutting operations are performed on the same work line as described above, die marks were still apt to be produced owing to insufficient adhesiveness of the lubricant on the cut metallic surface of the wire-shaped metal, in the wire drawing process following automatic flaw removal.
This invention was developed to overcome the above problems, and its second object is to provide a flaw-removal method and apparatus able to increase working efficiency for treatment of a wire-shaped metal, to reduce manufacturing costs, to prevent the increase in the number of cuts owing to a false defect detection and to prevent the appearance of die marks.